Ohm's Law / Circuit Calculator
Calculate voltage, current, resistance, or power for aircraft electrical circuits. Includes power wheel reference and wire heating guidance.
Solve For
Enter any two of: I and R, P and I, or P and R
Derived Values
Voltage
--
V
Current
--
A
Resistance
--
Ω
Power
--
W
Power Wheel
Each quadrant shows all formulas to solve for that variable
Why Resistance Matters in Aircraft Wiring
Excess resistance in aircraft wiring causes voltage drop and heat generation (P = I²R). Even a small resistance in a high-current circuit — like a starter motor or landing light circuit — can produce significant heat, leading to insulation degradation, chafing, or fire. Always verify wire gauge, connector condition, and termination quality when troubleshooting intermittent faults or overheating wires.
Typical Aircraft Circuit Reference
| System | Bus Voltage | Notes |
|---|---|---|
| Standard GA bus (single-engine) | 14V DC | Alternator + 12V battery |
| Standard GA bus (twin / turboprop) | 28V DC | Alternator + 24V battery |
| Large transport AC bus | 115V AC 400 Hz | 3-phase, IDG-driven |
| Emergency DC bus (transport) | 28V DC | Battery/APU backup |
| Avionics bus (GA) | 14 or 28V DC | Protected via avionics master |
Important Disclaimer
This tool is provided for educational and reference purposes only. Always verify all calculations against FAA-approved maintenance manuals, aircraft documentation, and applicable regulations. Never use web-based tools as the sole basis for airworthiness decisions.